Hydrangea plant named &#39;True Blue&#39;

ABSTRACT

A new and distinct cultivar of  Hydrangea macrophylla  (Thunb.) named ‘True Blue’ originated as a controlled cross between the cultivars ‘Blue Sky’ and ‘Blue Danube’. The cultivar ‘True Blue’ has blue—R.H.S. 100 A (blue group) sepals at maturity and is distinguished from other similar cultivars of which the inventor is aware by its sepal color, and its compact and sturdy growth habit. ‘True Blue’ has large showy inflorescences, having both sepalous and non-sepalous florets, although at maturity the sepalous florets hide the non-sepalous florets.

BOTANICAL CLASSIFICATION

Hydrangea macrophylla (Thunb.) ‘True Blue’

VARIETY DENOMINATION

‘True Blue’

BACKGROUND OF THE INVENTION

This invention relates to a new and distinct cultivar of theSaxifragaceae family. The botanical name of the plant is Hydrangeamacrophylla (Thunb.) ‘True Blue’.

The new cultivar originated as a seedling from a controlled crossbetween the commercial variety Hydrangea macrophylla (Thunb.) ‘BlueDanube’ and the commercial variety Hydrangea macrophylla (Thunb.) ‘BlueSky’.

The variety ‘True Blue’ has pigmented sepals, and is typically grownunder soil conditions with pH conditions that produce blue pigmentation.The new variety was first noticed, because it combined the desirablegrowth characteristics of its parents while producing flowers withsepals that have long-lasting pigmentation. The variety ‘True Blue’ hasstrong stems like its parent ‘Blue Sky’ and the compactness of itsparent ‘Blue Danube’. The florets of ‘True Blue’ are also glaucescent ascompared to the parent ‘Blue Danube’, and the panicle of ‘True Blue’ issignificantly larger than the panicle of ‘Blue Danube’.

The growth habit of ‘True Blue’ also distinguishes it from othervarieties of Hydrangea that have blue sepals of which the inventor isaware. ‘True Blue’ is more compact and its stems sturdier than the blue,commercially available variety ‘Mathilda’. The pedicels of ‘True Blue’also appear to be stronger, creating a stronger panicle than‘Henriksberg’, another commercially available, blue variety.

The new cultivar ‘True Blue’ has been successfully asexually reproducedunder controlled environmental conditions at a nursery in Half Moon Bay,Calif. under the direction of the inventor over a three year period withits distinguishing characteristics remaining stable.

‘True Blue’ is distinguished from other blue varieties of Hydrangea ofwhich the inventor is aware by the manner in which its sepals age andchange color. Sepal color of ‘True Blue’ is predominately blue atmaturity. The sepals of the very young, unopened florets are R.H.S. 145C (yellow-green group). Then, as the florets begin to age, the sepalsturn purple, and then white. The characteristic that distinguishes ‘TrueBlue’ from all other varieties known to the inventor is that as themature sepals age and turn purple they are highly resistant to burningand turning brown, unlike many other Hydrangeas. This makes the flowersof the plant more attractive for longer periods of time.

Asexual reproduction was first accomplished when vegetative cuttingswere taken from the initially selected plant. Examination of asexuallyreproduced, successive generations grown in at Half Moon Bay, Calif.show that the combination of characteristics as herein disclosed for‘True Blue’ remains firmly fixed through three generations.

DESCRIPTION OF THE DRAWINGS

The accompanying drawings consist of color photographs that show thetypical plant form, including the inflorescence, foliage, and sepals.

FIG. 1 is a view of the entire plant showing its form, compact growthhabit, dark green foliage, inflorescence, and blue sepals. Theparticular plant shown has only one panicle.

FIG. 2 is a view of the entire plant showing its form, compact growthhabit, dark green foliage, inflorescence, and blue sepals. Theparticular plant shown has multiple panicles.

FIG. 3 is a top view of the entire plant. The particular plant shown hasonly one panicle.

FIG. 4 is a top view of the entire plant. The particular plant shown hastwo panicles.

FIG. 5 is a close-up view of a panicle of the new variety, showingopened, sepalous florets.

FIG. 6 is a close-up view of a panicle of the new variety. The panicleshown is still rather young. The sepalous florets have not opened yet,and the pigmentation of the sepals is not complete.

FIG. 7 is a close-up view of a panicle of the new variety. Sepalousflorets have been moved to show the non-sepalous florets which arenormally hidden by the sepalous florets.

FIG. 8 is a close-up view of a mature floret of the new variety.

FIG. 9 is a close-up view of a mature floret of the new variety.

FIG. 10 is a close-up view of the adaxial surface of a mature leaf.

FIG. 11 is a close-up view of a non-woody portion of the stem, showinglenticels on the stem.

FIG. 12 is a close-up view of the base of the stem.

FIG. 13 is a close-up view of the underside of an individual sepalousfloret.

FIG. 14 is a close-up view of the abaxial surface of a mature leaf.

DESCRIPTION OF THE NEW PLANT

The plants shown in the figures are approximately 1 years old. The plantstarted out as cuttings, taken from the stem of a grown plant. Thecuttings were placed in a 4″ pot with hydrangea soil that would produceblue pigmentation in Hydrangeas that have pigmentation in their sepals.

‘True Blue’ has not been observed under all possible environmentalconditions. The phenotype may vary significantly with variations inenvironment such as temperature, light intensity and day length. Colordeterminations were made with The Royal Horticultural Society (R.H.S.)Colour Chart.

-   The plant:    -   -   Origin.—Controlled cross. Parents. — Hydrangea macrophylla            (Thunb.) ‘Blue Danube’ (unpatented) and Hydrangea            macrophylla (Thunb.) ‘Blue Sky’ (unpatented). Botanic            Classification. — Hydrangea macrophylla (Thunb.) True Blue’.        -   Form.—Upright, compact shrub. A typical plant with a mature            inflorescence that is ready for sale is approximately 17″            high and has a diameter of 16″ when grown in a 4″ pot with            appropriate soil amendments.        -   Growth.—Upright, vigorous growth habit. Inflorescence is            large. The plant branches easily with shoots forming at the            base of the plant. Lateral branches are similar in            appearance and form to the main stems.        -   Stems.—Lenticels are present. Stems become woody as they            age. The color of typical young stems and young lateral            branches is R.H.S. 145 A (green group). Woody stems are            R.H.S. 199 D (grey-brown group).        -   Foliage.—Abundant. Leaves are opposite on stem and lateral            branches. Shape of leaf. — Elliptic with acute base and            apex. Margins are serrate. Texture. — Glabrous; veins            dominate on the underside of the leaf and are sunken on the            leaf surface. Color. — Mature leaves have an upper side that            is R.H.S. 147 A (yellow-green group), and an under side that            is R.H.S. 147 B (yellow-green group). The upper side of            younger leaves can be a little lighter at R.H.S 137 A (green            group). The veins of mature leaves are R.H.S. 145 C            (yellow-green group) whether viewed from the top or the            bottom of the leaf. Leaves are pinnately veined. The midvein            and veins branching off the midvein are large and prominent            on the underside of the leaves.-   Buds:    -   -   Form.—Globose with 4 to 5 connate petals. Buds in the very            center of the inflorescence are non-sepalous. The majority            of buds have sepals. They are approximately 1 mm by 1 mm.            Very young floret buds are R.H.S. 145C (yellow-green group).        -   Aspect.—Smooth.        -   Arrangement.—Borne on branched panicles.-   Inflorescence:    -   -   Form.—Paniculate. Terminal. As many as 100 or more            individual flowers (florets) per inflorescence. Both            sepalous florets and non-sepalous florets borne on same            panicle with the sepalous florets hiding the non-sepalous            florets, when the inflorescence reaches maturity. An            inflorescence with 100 florets may have as many as 85            sepalous florets and 15 non-sepalous florets. Flowers do not            produce a fragrance. The peduncle or panicle for the            inflorescence is strong and upright. The uppermost portions            of the pedicels for the individual florets are predominately            blue — R.H.S. 94 A (violet-blue group) at maturity.        -   Size of inflorescence.—Large. Individual inflorescence size            is dependent on the number of florets. A typical            inflorescence can grow as large as 9″ in diameter, and 4″            high.        -   Shape.—Clusters of numerous small florets; sepalous florets            are flat and overlapping one another. Sepals are persistent.        -   Appearance.—Showy.-   Florets:    -   -   General.—The non-sepalous florets at the center of the            inflorescence open first. Sepalous florets are perfect and            complete, although petals, stamens and ovary generally fall            off as floret approaches maturity. Corolla: Generally there            are 4 petals that are blue — R.H.S. 100 A (blue group). In            the sepalous florets, the petals generally fall off before            the inflorescence reaches maturity.-   Reproductive organs:    -   -   Stamens.—10 stamens. Pollen is yellow — R.H.S. 8A (yellow            group). Plant produces abundant pollen. Filament is blue —            R.H.S. 100 A and approximately 2 mm long. Anther is 1 mm            long and is regular and basally attached.        -   Stigma.—Two to three-pronged stigma on one pistil per            floret. Stigma is violet-blue — R.H.S. 93 A (violet-blue            group) and barely protrudes from the ovary.        -   Ovary.—Ovary is blue — R.H.S. 100 A (blue group) and is            partially inferior.        -   Sepalous florets.—General. — Veins dominate on the underside            of the sepals. Number of sepals. — 4 or 5 sepals per floret,            usually 4. Aspect of sepals. — Smooth and glaucescent. Shape            of sepals. — Reniform with acuminate apex. Edges often wavy            when the floret is young. Size of sepals. — As the florets            mature, the sepals enlarge and overlap each other more and            more, until, often, there is no space between the sepals            when the petals of the florets open. Usually 1 dominant            sepal, 2 smaller but equally-sized sepals, and 1 small            sepal. Largest sepal at maturity is typically 3 cm long and            2.7 cm wide, the medium sized sepals are typically 2.4 cm            long by 2.3 cm wide, and the smallest sepals are typically            2.0 cm long and 2 cm wide).        -   Coloration of sepals.—Development of the blue color of the            sepals at maturity starts in the tips of the petals. As the            pigment at the tips of the sepals turns blue, the base of            the sepals will be white — R.H.S. 155 A (white group). The            color of the underside of the sepals may be slightly            lighter. At maturity the sepals are predominantly blue —            R.H.S 100D (blue group). As the sepals age, the veins at the            base of the sepals and the tips of the sepals turn violet —            R.H.S. 87 C (violet group).        -   Fruit.—none.

1. A new and distinct Hydrangea macrophylla plant named ‘True Blue’substantially as herein shown and described.